Rumer Willis Explains the Back Brace Photo

Rumer Willis may be best known for her famous parents, Bruce Willis and Demi Moore, but a recent photo proves the 18-year-old is no slouch on the set of her new film.

Last week, a picture of the actress, who stars in the upcoming comedy House Bunny, was leaked featuring her character wearing just a dunce cap and silver back brace.

"That picture was taken from a photo shoot we did for the movie for a calendar in the film that shows [the sorority girls] going too far," Willis told PEOPLE Saturday during an Art of Elysium benefit held at the French Connection Beach House in Malibu. "Somebody happened to take a picture and leak it. It is what it is."

But Willis, who often gets advice about the business from her movie star mom and dad, took the leak in stride.

"I've been really lucky," Willis said. "I'm so grateful to have [my parents], who have worked so much and so diversely in this business, when I go out on auditions or when I have questions about stuff."

Willis, the eldest of Bruce and Demi's three daughters, has had bit parts in her parents' movies until now – moving on to stronger supporting roles in House Bunny and the indie thriller From Within.

"The girls I'm working with are such sweethearts, and I tend to not like girls, and I think most of my costars are the same way but we all get along so well," she said.

Those House Bunny costars include American Idol runner-up Katharine McPhee and Scary Movie star Anna Faris, who plays a recently-fired centerfold who signs up to be the house mother at the nerdiest sorority on campus. Willis plays an insecure student who wears a back brace even though she could have had it removed years ago.

Despite some drama on the Maryland set of From Within when a man was arrested on drug charges in a hotel room where she was present, Willis said she is currently enjoying that film role as well.

"It's unbelievable – I've been on a lot of movie sets in my life and it's amazing to be a part of a production where it's about everything coming together as a whole and everyone working towards making it a great picture," she said.

In addition to acting you can expect Willis to have her own diverse career that includes photography, music and maybe even a fashion line.

"I love a lot of different things," said the actress who turns 19 on Thursday. "I really like acting, I really like music and I love photography. In a perfect world I could do all three. In the future, I would love to do an album. I have been singing since I was really little which not a lot of people know about so it's one of those fun, personal things."